Astrobites@Austin: Monday Morning Sessions

This year, Astrobites will be liveblogging AAS. In order to avoid inundating our readers’ RSS feeds, we’ll be updating this post with short paragraphs about the talks we’ve heard and posters we’ve seen. So keep checking back throughout Monday morning!
– Dan Gifford, Susanna Kohler, Elisabeth Newton, Adele Plunkett and Evan Schneider

11:45am – Press Release: How to Build a Milky Way

The SEGUE survey – Connie Rockosi & Judy Cheng, UC Santa Cruz

SEGUE is an SDSS III project that surveys old stars in the thick disk of the Milky Way. By measuring the positions, chemical composition and motions of these stars, this survey is designed to study how the Milky Way disk formed. SEGUE is a wide field, very sensitive instrument, which allows it to look at many stars at once over large distances. One of the results of the SEGUE survey is an investigation of how the thick disk of the Milky Way formed – did it start out thick, or did a thin disk get puffed up through stellar interactions? A metallicity gradient in the thick disk – in which stars further out in the galaxy have lower metallicities – could be an indication of a thick disk that formed “inside-out”, from thin disk stars. No gradient could imply either that all the thick disk stars formed rapidly, or that mixing between the thin and thick disk stars happens very efficiently. Cheng and collaborators see no gradient in the thick disk stars, indicating rapid, in situ formation and/or thorough mixing.

A sister survey of SEGUE, APOGEE is the first spectroscopic survey to attempt a comprehensive look at the Milky Way, including dusty regions like the Galactic disk and bulge. APOGEE’s goal is to understand the structure, dynamics, and evolution of all the pieces of the Milky Way, and their relation to each other. APOGEE employs a sophisticated fiber optic system and holographic silicon spectrograph to peer into the heart of the Milky Way.

Tracy Delaney gave an engaging talk about the supernova remnant of Cas A. She presented a 3-D mapping of the various components of shocked ejecta, including oxygen and silicon. She also investigated why no shocked iron was observed, and estimated the mass of unshocked gas in this region. The goal was to measure the total density and mass of the SNR, a rather complicated picture. Aside from the exciting science, what she did well was to explain each individual component of an animated map, using colors and cartoons. All of this was delivered with exuberance and and clear explanations throughout her talk.

Catherine Heymans opened with an animation of the Millennium Simulation, showing the structure of the Universe painted in dark matter. She talked about the “giant cosmic battle” between dark matter, pulling matter together, and dark energy, driving it apart. The CFHT Lensing Survey has constructed a dark matter map, the largest ever made. They use weak gravitational lensing – where the light from background galaxies is distorted by the mass of objects in the foreground – to construct the map. It shows us the structure of dark matter in the Universe, with lumps, filaments and voids. The map agrees well with expectations of the web-like structure seen in simulations, such as the Millennium Simulation.

8:30am – The Kavli Lecture: The CMB and Neutrinos – Lyman Page

The first invited lecture of the 219th AAS was given by Dr. Lyman Page of Princeton University. Dr. Page studies the Cosmic Microwave Background (CMB), which has been measured extremely accurately at large angular scales by the WMAP satellite. In contrast to the accuracy of CMB measurements, no one has measured the neutrino background, despite the fact that its energy density is hundreds of times higher. This, of course, is because neutrinos are incredibly weakly interacting particles, making them almost impossible to detect. Nevertheless, neutrinos should not be ignored, because their mass, though small, does play a role in the matter budget of the universe. Using data from the Atacama Cosmology Telescope (ACT), Dr. Page and his team are measuring the high multipole tail of the CMB power spectrum (this corresponds to small angular scales). This part of the power spectrum is dominated by Silk Damping; by carefully measuring the damping, constraints can be placed on the number of relativistic species (like neutrinos), which increase the damping.

8am – Careers 101: Career Planning Workshop for Graduate Students and Postdocs with Alaina Levine

My first session of the day (8 am, good morning!) was a workshop given by Alaina Levine, the founder of Quantum Success Solutions. The workshop was organized around a panel of astronomers with diverse careers, with each panelist introducing him/herself, followed with commentary from Alaina Levine, and finally time for questions from the audience comprised of mostly graduate students. It appears that career potential is a common concern for graduate students, enough to fill a room with inquiring and aspiring scientists-in-training. To document some of the useful advice emphasized in this workshop, I will follow this brief post with a more detailed review of the discussion, so check back later today. Three take away messages: (1) your reputation is your greatest asset, (2) successful people do what less successful people are not willing to do, and (3) network and market yourself. A meeting like this is an ideal place to develop that networking, and I’m off to do just that!

8am – Welcome Address

Good morning from Austin! Dr. Debra Elmegreen gave a great opening address where she highlighted great progress in AAS over the recent year and new initiatives and programs for 2012. A very exciting announcement came in the introduction of a new division of the AAS, Laboratory Astrophysics, which is the first new such division in 30 years! Congratulations to those in the laboratory astrophysics community which is now represented at a greater level within the overall astronomical community. She also discussed the AAS Communication with Washington Initiative which brings astronomy ambassadors to The Hill in D.C. once a week to speak with our government. As always, you too can make an impact by talking with your own local representatives about the importance of astronomy in scientific progress. There was also congrats given to the 2012 Rodger Doxey Travel Prize winners: Sarah Ballard, Jonathon C. Bird, Geoffrey Mathews, Ashley Pagnotta, Adric R. Riedel, Barbara Denisse Rojas Ayala, Sumin Tang, and Gail Zasowski.